Flip-chip mounting method and bump formation method

ABSTRACT

To provide a flip-chip mounting method and a bump formation method applicable to flip-chip mounting of a next generation LSI and having high productivity and high reliability. 
     A semiconductor chip  20  having a plurality of electrode terminals  12  is held to oppose a circuit board  21  having a plurality of connection terminals  11  with a given gap provided therebetween, and the semiconductor chip  20  and the circuit board  21  in this state are dipped in a dipping bath  40  containing a melted resin  14  including melted solder particles for a given period of time. In this dipping process, the melted solder particles self-assemble between the connection terminals  11  of the circuit board  21  and the electrode terminals  12  of the semiconductor chip  20 , so as to form connectors  22  between these terminals. Thereafter, the semiconductor chip  20  and the circuit board  21  are taken out of the dipping bath  40 , and the melted resin  14  having permeated into the gap between the semiconductor chip  20  and the circuit board  21  is cured, so as to complete a flip-chip mounting body.

RELATED APPLICATIONS

This application is a national phase of PCT/JP2006/304351 filed on Mar.7, 2006, which claims priority from Japanese Application No. 2005-072526filed on Mar. 15, 2005, the disclosures of which Applications areincorporated by reference herein. The benefit of the filing and prioritydates of the International and Japanese Applications is respectfullyrequested.

TECHNICAL FIELD

The present invention relates to a flip-chip mounting method formounting a semiconductor chip on a circuit board and a method forforming a bump on an electrode of a substrate.

BACKGROUND ART

Recently, in accordance with the increased density and the increaseddegree of integration of semiconductor integrated circuits (LSIs) usedin electronic equipment, the number of electrode terminals of an LSIchip has been rapidly increased and the pitch therebetween has beenrapidly reduced. In mounting such an LSI chip on a circuit board,flip-chip mounting is widely employed for reducing interconnect delay.Generally, in the flip-chip mounting, solder bumps are formed onelectrode terminals of an LSI chip and the electrode terminals of theLSI chip are connected as a whole to connection terminals formed on acircuit board through the solder bumps.

However, in order to mount a next generation LSI including electrodeterminals in the number exceeding 5,000 on a circuit board, it isnecessary to form bumps correspondingly to a fine pitch of 100 μm orless, but it is difficult to cope with this fine pitch by the currentsolder bump forming technology. Also, since bumps in the large numbercorresponding to the number of electrode terminals should be formed, inorder to reduce the cost, it is desired to attain high productivity byreducing mounting tact time per chip.

Similarly, in accordance with the increased number of electrodeterminals, the arrangement of electrode terminals of semiconductorintegrated circuits has been changed to area array arrangement fromperipheral arrangement. Furthermore, in order to meet the demands for ahigher density and a higher degree of integration, the semiconductorprocess is expected to be developed from 90 nm process to 65 nm or 45 nmprocess. As a result, the refinement of interconnects is furtherproceeded, and the capacitance between interconnects is increased.Therefore, problems of a rapid operation and a power consumption losshave become serious, and there are increasing demands for reducing thedielectric constant (i.e., attaining low-k) of an insulating filmprovided between interconnect layers. The low-k of such an insulatingfilm can be realized by making the material for the insulating filmporous, and therefore, such a film is poor in the mechanical strengthand hence is an obstacle to thickness reduction of a semiconductor.Moreover, in the case where electrode terminals are formed in the areaarray arrangement, since the porous film has a problem of the strengthdue to its low-k, it is difficult to form bumps on the electrodeterminals in the area array arrangement and to perform the flip-chipmounting itself. Accordingly, there is a demand for a small-loadflip-chip mounting method suitably employed for a thin and high-densitysemiconductor coping with the future development of the semiconductorprocess.

As a technique for forming bumps, a plating method or a screen printingmethod is conventionally developed. Although the plating method issuitable for attaining a fine pitch, the process is complicated and isdisadvantageous in the productivity. Alternatively, the screen printingmethod is good at productivity but is not suitable for attaining a finepitch because a mask is used.

Under these circumstances, some techniques for forming solder bumps onelectrodes of an LSI chip or a circuit board have been recentlydeveloped. These techniques are not only suitable for forming fine bumpsbut also good at productivity because bumps can be formed as a whole,and hence are regarded to be applicable to the mounting of a nextgeneration LSI on a circuit board.

For example, in a technique disclosed in Patent Document 1, solder pastemade of a mixture of a solder powder and a flux is solidly applied on asubstrate on which electrodes have been formed, and the solder powder ismelted by annealing the substrate, so as to selectively form solderbumps on the electrodes with high wettability.

Alternatively, in a technique disclosed in Patent Document 2, a pastecomposition including an organic acid lead salt and metal tin asprincipal components (chemical reaction depositing solder) is solidlyapplied on a substrate on which electrodes have been formed, and asubstitution reaction between Pb and Sn is caused by annealing thesubstrate, so as to selectively deposit Pb/Sn alloy on the electrodes ofthe substrate.

However, in both of the techniques disclosed in Patent Documents 1 and2, the paste composition is supplied onto the substrate throughapplication, and hence, variation in thickness and concentration islocally caused. Therefore, the amount of depositing solder is differentamong the electrodes, and hence, the bumps cannot be formed in a uniformheight. Also, in these methods, since the paste composition is suppliedby the application onto the irregular surface of the circuit board wherethe electrodes have been formed, a sufficient amount of solder cannot besupplied onto the electrodes corresponding to convex portions, andtherefore, it is difficult to attain a desired height of bumps necessaryfor the flip-chip mounting.

In the flip-chip mounting employing the conventional bump formationmethod, after mounting a semiconductor chip on a circuit board wherebumps have been formed, it is necessary to further perform a procedurefor injecting a resin designated as an underfill resin into a spacebetween the semiconductor chip and the circuit board for fixing thesemiconductor chip on the circuit board.

Therefore, as a method for simultaneously obtaining electric connectionbetween opposing electrode terminals of a semiconductor chip and acircuit board and fixing the semiconductor chip on the circuit board, aflip-chip mounting technique using an isotropic conducting material(see, for example, Patent Document 3) has been developed. In thismethod, a thermosetting resin including conducting particles is suppliedbetween a circuit board and a semiconductor chip and a pressure isapplied to the semiconductor chip at the same time as the thermosettingresin is annealed. Thus, the electric connection between the electrodeterminals of the semiconductor chip and the circuit board and thefixation of the semiconductor chip on the circuit board can besimultaneously realized.

-   Patent Document 1: Japanese Laid-Open Patent Publication No.    2000-94179-   Patent Document 2: Japanese Laid-Open Patent Publication No.    1-157796-   Patent Document 3: Japanese Laid-Open Patent Publication No.    2000-332055

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the flip-chip mounting using an anisotropic conducting material,however, electric conductance between the electrodes is obtained bymechanical contact through the conducting particles, and therefore, itis difficult to obtain a stable conducting state.

Also, since the conducting particles sandwiched between the opposingelectrodes are kept by cohesion obtained through the thermal curing ofthe resin, it is necessary to adjust the characteristics of thethermosetting resin such as the elastic coefficient and the coefficientof thermal expansion and the characteristics of the conducting particlessuch as the grain size distribution, and therefore, the process isdisadvantageously difficult to control.

Specifically, the flip-chip mounting using an isotropic conductingmaterial still has a large number of problems in the productivity andthe reliability for the application to a next generation LSI chip havingconnection terminals in the number exceeding 5,000.

The present invention was devised in consideration of these conventionalcircumstances, and an object is providing a flip-chip mounting methodwith high productivity and high reliability applicable to flip-chipmounting of a next generation LSI. Another object is providing a bumpformation method in which the technique of the flip-chip mounting methodof the invention is applied to formation of bumps.

Means for Solving Problems

The flip-chip mounting method of this invention in which a semiconductorchip having a plurality of electrode terminals is aligned to oppose acircuit board having a plurality of connection terminals forelectrically connecting the connection terminals of the circuit boardand the electrode terminals of the semiconductor chip to each other,includes the steps of: holding the semiconductor chip to oppose thecircuit board with a given gap provided therebetween; and dipping thesemiconductor chip and the circuit board held with the given gap in adipping bath containing a melted resin including melted solderparticles, and in the step of dipping, the melted solder particlesself-assemble between the connection terminals of the circuit board andthe electrode terminals of the semiconductor chip, whereby formingconnectors between the terminals.

The step of dipping is preferably performed while rocking thesemiconductor chip and the circuit board held with the given gap withinthe dipping bath. Alternatively, the step of dipping is preferablyperformed while allowing the melted resin contained in the dipping bathto flow.

In one preferable aspect, the flip-chip mounting method furtherincludes, after the step of dipping, a step of taking the semiconductorchip and the circuit board out of the dipping bath and curing the meltedresin having permeated into the gap between the semiconductor chip andthe circuit board.

In one preferable aspect, in the step of holding the semiconductor chip,the semiconductor chip is held to oppose the circuit board with thegiven gap provided therebetween by holding the semiconductor chip andthe circuit board with a fixing jig.

Furthermore, the step of holding the semiconductor chip includes a stepof holding a plurality of semiconductor chips and a plurality of circuitboards with the fixing jig, whereby holding each of the semiconductorchips to oppose each of the circuit boards with a given gap providedtherebetween, and the step of dipping is performed as batch processingfor dipping the plurality of semiconductor chips and the plurality ofcircuit boards simultaneously in the dipping bath.

The step of dipping is preferably performed with a pressure in thedipping bath reduced.

In one preferable aspect, the step of dipping is performed in a dippingbath in which the melted resin has a temperature gradient, and thesolder particles included in the melted resin are kept in an unmeltedstate in a low temperature region and are kept in a melted state in ahigh temperature region, and the semiconductor chip and the circuitboard held with the given gap are dipped in the low temperature regionof the dipping bath for a given period of time before being dipped inthe high temperature region for a given period of time.

The bump formation method of this invention for forming bumps onelectrodes of a substrate having a plurality of electrodes, includes thesteps of holding a flat plate to oppose the substrate with a given gapprovided therebetween; and dipping the substrate and the flat plate heldwith the given gap in a dipping bath containing a melted resin includingmelted solder particles, and in the step of dipping, the melted solderparticles self-assemble on the electrodes of the substrate, wherebyforming bumps on the electrodes.

In one preferable aspect, the bump formation method further includes,after the step of dipping, a step of taking the substrate and the flatplate out of the dipping bath and removing the flat plate and the meltedresin having permeated into the gap between the substrate and the flatplate.

A plurality of metal patterns in substantially the same shape as theelectrodes are preferably formed on the flat plate in positions opposingthe plurality of electrodes formed on the substrate.

Furthermore, the substrate is preferably a circuit board, asemiconductor chip or a semiconductor wafer.

The mounting apparatus of this invention for flip-chip mounting asemiconductor chip on a circuit board, includes a fixing jig for holdingthe semiconductor chip and the circuit board with a given gap providedtherebetween; a dipping bath containing a melted resin including meltedsolder particles; and a conveyor for conveying the fixing jig into thedipping bath, and the fixing jig holding the semiconductor chip and thecircuit board is dipped in the dipping bath by the conveyor and themelted solder particles are made to self-assemble between connectionterminals of the circuit board and electrode terminals of thesemiconductor chip, whereby forming connectors between the terminals.

The other mounting apparatus of this invention for forming bumps onelectrodes of a substrate having a plurality of electrodes, includes afixing jig for holding a flat plate in a position to oppose thesubstrate with a given gap provided therebetween; a dipping bathcontaining a melted resin including melted solder particles; and aconveyor for conveying the fixing jig into the dipping bath, and thefixing jig holding the substrate and the flat plate is dipped in thedipping bath by the conveyor and the melted solder particles are made toself-assemble on the electrodes of the substrate, whereby forming bumpson the electrodes.

The conveyor preferably includes means for causing rocking movementwithin the dipping bath. Alternatively, the dipping bath preferablyincludes means for allowing the melted resin to flow in the dippingbath.

In one preferable aspect, the mounting apparatus further includesannealing means, and the fixing jig holding the semiconductor chip andthe circuit board or the substrate and the flat plate is taken out ofthe dipping bath and is transferred to the annealing means, wherebythermally curing the melted resin having permeated into the gap betweenthe semiconductor chip and the circuit board or between the substrateand the flat plate.

The fixing jig is preferably able to hold a plurality of pairs of thesemiconductor chip and the circuit board or the substrate and the flatplate.

In one preferable aspect, the mounting apparatus further includes aparticle counter, and the number or grain size of the melted solderparticles included in the melted resin is measured with the particlecounter for controlling quality of the dipping bath.

In one preferable aspect, the dipping bath is connected to a circulatingapparatus for circulating the melted resin including the melted solderparticles, and the melted solder particles included in the melted resincontained in the dipping bath is kept in a given ratio by making themelted resin including the melted solder particles circulate between thedipping bath and the circulating apparatus.

The other flip-chip mounting method of this invention in which a circuitboard having a plurality of connection terminals is aligned to oppose asemiconductor chip having a plurality of electrode terminals forelectrically connecting the connection terminals of the circuit boardand the electrode terminals of the semiconductor chip to each other,includes the steps of holding the semiconductor chip to oppose thecircuit board with a given gap provided therebetween; dipping thesemiconductor chip and the circuit board held with the given gap in adipping bath containing a melted resin including solder particles and aconvection additive for a given period of time; and annealing the meltedresin having permeated into the gap between the semiconductor chip andthe circuit board after taking the semiconductor chip and the circuitboard out of the dipping bath, and in the step of annealing, the solderparticles are melted and the convection additive is boiled to convectwithin the melted resin for making the melted solder particlesself-assemble between the connection terminals of the circuit board andthe electrode terminals of the semiconductor chip, whereby formingconnectors between the terminals.

In one preferable aspect, the flip-chip mounting method furtherincludes, after the step of annealing, a step of fixing thesemiconductor chip on the circuit board by curing the melted resinhaving permeated into the gap between the semiconductor chip and thecircuit board.

The other bump formation method of this invention for forming bumps onelectrodes of a substrate having a plurality of electrodes, includes thesteps of holding a flat plate in a position to oppose the substrate witha given gap provided therebetween; dipping the substrate and the flatplate held with the given gap in a dipping bath containing a meltedresin including solder particles and a convection additive for a givenperiod of time; and annealing the melted resin having permeated into thegap between the substrate and the flat plate after taking the substrateand the flat plate out of the dipping bath, and in the step ofannealing, the solder particles are melted and the convection additiveis boiled to convect within the melted resin for making the meltedsolder particles self-assemble on the electrodes of the substrate,whereby forming bumps on the electrodes.

EFFECTS OF THE INVENTION

In the flip-chip mounting method of this invention, a semiconductor chipand a circuit board held with a given gap provided therebetween aredipped in a dipping bath containing a melted resin including meltedsolder particles, so that the melted solder particles dispersed in themelted resin can be constantly supplied to the gap between thesemiconductor chip and the circuit board. Therefore, bond of the meltedsolder particles is uniformly proceeded in the gap. As a result, themelted solder particles uniformly grown self-assemble between connectionterminals of the circuit board and electrode terminals of thesemiconductor chip with high wettability, and hence, connectors forelectrically connecting the electrode terminals and the connectionterminals to each other can be uniformly formed.

Furthermore, when the semiconductor chip and the circuit board held withthe given gap are dipped while being rocked in the dipping bath or whileallowing the melted resin contained in the dipping bath to flow, themelted solder particles dispersed in the melted resin can be moreforcedly supplied to the gap between the semiconductor chip and thecircuit board, and hence, the bond of the melted solder particles can beuniformly proceeded in a balanced manner. As a result, more uniformconnectors can be formed between the electrode terminals and theconnection terminals. In addition, since the melted solder particlesdispersed in the melted resin can be efficiently incorporated into thegap, the ratio of the melted solder particles to be included in themelted resin can be set to be small, and hence, quality control of thedipping bath can be easily performed.

Moreover, after forming the connectors between the terminals of thecircuit board and the semiconductor chip in the dipping bath, thecircuit board and the semiconductor chip are taken out of the dippingbath and the melted resin having permeated into the gap between thecircuit board and the semiconductor chip is cured. Thus, electricconnection between the semiconductor chip and the circuit board andfixation of the semiconductor chip on the circuit board can be bothperformed through a series of procedures, and therefore, flip-chipmounting with high productivity can be realized.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A through 1C are cross-sectional views for showing procedures ina flip-chip mounting method using a resin including a convectionadditive.

FIGS. 2A through 2D are cross-sectional views for showing procedures ina flip-chip mounting method according to Embodiment 1 of the invention.

FIG. 3 is a cross-sectional view for showing the structure of a fixingjig used in Embodiment 1 of the invention.

FIG. 4 is a cross-sectional view for showing an aspect of a dipping bathused in Embodiment 1 of the invention.

FIGS. 5A and 5B are cross-sectional views for showing an aspect of thedipping bath used in Embodiment 1 of the invention.

FIGS. 6A through 6D are cross-sectional views for showing procedures ina bump formation method according to Embodiment 2 of the invention.

FIG. 7 is a diagram for showing the structure of a mounting apparatusaccording to Embodiment 3 of the invention.

FIG. 8 is a diagram for showing the structure of a dipping bath used inEmbodiment 3 of the invention.

FIGS. 9A through 9D are cross-sectional views for showing procedures ina flip-chip mounting method according to Embodiment 4 of the invention.

FIGS. 10A through 10E are cross-sectional views for showing proceduresin a bump formation method according to Embodiment 4 of the invention.

DESCRIPTION OF REFERENCE NUMERALS

-   -   10 circuit board    -   11 connection terminal    -   12 electrode terminal    -   13, 14 resin    -   15 convection additive    -   20 semiconductor chip    -   21 circuit board    -   22 connector    -   25 substrate    -   26 flat plate    -   27 electrode    -   28 bump    -   30, 31 fixing jig    -   40, 40 a, 40 b dipping bath    -   50 mounting apparatus    -   60 conveyor    -   70 annealing means    -   80 particle counter    -   90 circulating apparatus    -   91, 92 connecting pipe

BEST MODE FOR CARRYING OUT THE INVENTION

The present applicant has examined flip-chip mounting applicable to anext generation LSI chip and proposed a novel flip-chip mounting methodin which fine bumps can be uniformly formed in Japanese PatentApplication No. 2004-267919.

FIGS. 1A through 1C are diagrams for showing basic procedures in theflip-chip mounting method disclosed in the description of the patentapplication by the present applicant.

First, as shown in FIG. 1A, a resin 13 including solder particles (notshown) and an additive 15 is supplied onto a circuit board 21 where aplurality of connection terminals 11 are formed.

Next, as shown in FIG. 1B, the surface of the resin 13 supplied onto thecircuit board 21 is brought into contact with a semiconductor chip 20.At this point, the semiconductor chip 20 having a plurality of electrodeterminals 12 are aligned to oppose the circuit board 21 having theplural connection terminals 11. Under this condition, the resin 13 isannealed, so as to melt the solder particles dispersed in the resin 13.

The melted solder particles are bonded to one another within the resin13 as shown in FIG. 1C and self-assemble between the connectionterminals 11 and the electrode terminals 12 with high wettability, so asto form connectors 22. Ultimately, the resin 13 is cured so as to fixthe semiconductor chip 20 on the circuit board 21, and thus, a flip-chipmounting body is completed.

This method is characterized by that the resin 13 including the solderparticles further includes the additive 15 boiled at a temperature wherethe solder particles are melted. Specifically, at the temperature wherethe solder particles are melted, the additive 15 included in the resin13 (hereinafter referred to as the convection additive) is boiled and isconvected within the resin 13, so as to accelerate the movement of themelted solder particles dispersed within the resin 13, which proceedsuniform bond of the melted solder particles. As a result, the meltedsolder particles uniformly grown self-assemble between the connectionterminals 11 of the circuit board 21 and the electrode terminals 12 ofthe semiconductor chip 20 with high wettability, so that the connectors22 with high uniformity can be formed between the connection terminals11 and the electrode terminals 12.

It can be regarded that the resin 13 including the solder particlesworks as a “sea” where the melted solder particles can freely float andmove. However, since the bonding process of the melted solder particlesis completed in a very short period of time, even when the “sea” wherethe melted solder particles can move is provided, the bond is proceededmerely locally and it is difficult to uniformly bond the melted solderparticles to one another.

In other words, in the above-described method, means for forcedly movingthe melted solder particles is additionally provided by furtherincluding the convection additive 15 in the resin 13 including thesolder particles.

The convection additive 15 may be any additive as far as it is boiledwhen the resin 13 is annealed at the temperature where the solderparticles are melted, and for example, isopropyl alcohol, butyl acetate,butyl Carbitol, ethylene glycol or the like can be used in accordancewith the melting point of the used solder particles.

The present invention is based on a similar technical point of view, andmelted solder particles are made to efficiently self-assemble betweenterminals by a method different from that described above, so as toprovide a novel flip-chip mounting method for realizing formation ofuniform connectors.

Preferred embodiments of the invention will now be described withreference to the accompanying drawings. In the drawings referred tobelow, like reference numerals are used to refer to like elements havingsubstantially the same function for simplifying the description. It isnoted that the present invention is not limited to the embodimentsdescribed below.

Embodiment 1

FIGS. 2 a through 2 d are cross-sectional views for showing basicprocedures in a flip-chip mounting method according to Embodiment 1 ofthe invention.

First, as shown in FIG. 2A, a semiconductor chip 20 having a pluralityof electrode terminals 12 is held by a fixing jig 30 so as to oppose acircuit board 21 having a plurality of connection terminals 11 with agiven gap (of, for example, 10 through 100 μm) provided therebetween. Atthis point, the electrode terminals 12 of the semiconductor chip 20 andthe connection terminals 11 of the circuit board 10 are aligned tooppose each other.

At this point, the fixing jig 30 may be anything as far as it can fixthe semiconductor chip 20 and the circuit board 21 with the given gapprovided therebetween, and a spacer may be inserted between thesemiconductor chip 20 and the circuit board 21 for keeping the givengap.

Next, as shown in FIG. 2B, the semiconductor chip 20 and the circuitboard 21 held with the given gap are dipped in a dipping bath 40containing a melted resin (such as epoxy resin) 14 including meltedsolder particles (such as Sn—Ag-based solder) for a given period oftime. At this point, the melted resin 14 permeates into the gap betweenthe semiconductor chip 20 and the circuit board 21, and the gap isfilled with the melted resin 14. It is noted that the dipping bath 40 iskept at a temperature where the solder particles are melted (forexample, 150 through 250° C.).

In this dipping process, the melted solder particles dispersed withinthe resin 14 self-assemble between the connection terminals 11 and theelectrode terminals 12 with high wettability, so as to form connectors22 between the terminals as shown in FIG. 2C. It is noted that thedipping time is typically preferably approximately 5 through 60 secondsdepending upon the amount of melted solder particles dispersed in themelted resin 14.

At this point, since the melted resin 14 can freely permeate into thegap between the semiconductor chip 20 and the circuit board 21 dipped inthe dipping bath 40, the melted solder particles dispersed in the meltedresin 14 are constantly supplied to the gap between the semiconductorchip 20 and the circuit board 21 as a result, and hence, the bond of themelted solder particles can be uniformly proceeded in the gap.

When the semiconductor chip 20 and the circuit board 21 held with thegiven gap are dipped in the dipping bath 40 while being rocked in thedirection of an arrow shown in FIGS. 2B and 2C, the melted solderparticles dispersed in the melted resin 14 can be more forcedly suppliedto the gap between the semiconductor chip and the circuit board,resulting in proceeding the bond of the melted solder particles moreuniformly. Also, the same effect can be attained by dipping them whileallowing the melted resin contained in the dipping bath to flow.

Next, after forming the connectors 22, as shown in FIG. 2D, thesemiconductor chip 20 and the circuit board 21 are taken out of thedipping bath 40, and the melted resin 14 having permeated into the gapbetween the semiconductor chip 20 and the circuit board 21 is cured, soas to fix the semiconductor chip 20 on the circuit board 21, and thus, aflip-chip mounting body is completed.

Since the gap between the semiconductor chip 20 and the circuit board 21is so small to the extent that the connectors 22 can be formed (and istypically, 10 through 80 μm), even after taking the semiconductor chip20 and the circuit board 21 out of the dipping bath 40, the melted resin14 having permeated into the gap stays in the gap and does not flow outbecause it has given viscosity.

According to the present invention, the melted solder particlesdispersed in the melted resin 14 are constantly supplied to the gapbetween the semiconductor chip 20 and the circuit board 21 by dippingthe semiconductor chip 20 and the circuit board 21 held with the givengap in the dipping bath 40 containing the melted resin 14 including themelted solder particles. Therefore, the bond of the melted solderparticles can be uniformly proceeded in the gap. Accordingly, the meltedsolder particles uniformly grown self-assemble between the connectionterminals of the circuit board and the electrode terminals of thesemiconductor chip with high wettability, so as to uniformly form theconnectors for electrically connecting the terminals to each other.

Furthermore, when the semiconductor chip 20 and the circuit board 21held with the given gap are dipped in the dipping bath 40 while beingrocked, or when they are dipped while allowing the melted resin 14 toflow in the dipping bath 40, the melted solder particles dispersed inthe melted resin 14 can be more forcedly supplied to the gap between thesemiconductor chip 20 and the circuit board 21, and hence, the bond ofthe melted solder particles can be more uniformly proceeded. As aresult, the connectors can be more uniformly formed between theterminals of the semiconductor chip 20 and the circuit board 21.

The melted resin 14 contained in the dipping bath 40 includes the meltedsolder particles in a given ratio, and the melted solder particles aresupplied for forming the connectors 22 for connecting the terminals ofthe semiconductor chip 20 and the circuit board 21, and therefore, themelted resin 14 should include the solder particles at least in theamount sufficient for forming the connectors 22.

If the melted resin 14 including the solder particles is supplied onto alimited area on the surface of the circuit board 21 (or thesemiconductor chip 20) by the method shown in FIG. 1A, the minimumamount of solder particles to be included in the melted resin 14 isequivalent to the ratio of all the connection terminals 11 (or theelectrode terminals 12) occupied on the surface of the circuit board 21(or the semiconductor chip 20). This amount depends upon the arrangementof the connection terminals 11, and for example, when an area array isassumed to be employed, the melted resin 14 should include 15 through 30vol % of solder particles.

On the contrary, in the method of this invention in which thesemiconductor chip 20 and the circuit board 21 are dipped in the dippingbath 40 containing the melted resin 14, the solder particles dispersedin the melted resin 14 can be incorporated into the gap between thesemiconductor chip 20 and the circuit board 21 at any time, andtherefore, the ratio of the melted solder particles to be included inthe melted resin 14 can be much smaller than in the method shown in FIG.1A.

In particular, when the semiconductor chip 20 and the circuit board 21are rocked within the dipping bath 40 or the melted resin 14 is allowedto flow within the dipping bath 40 in the dipping process, the meltedsolder particles can be more smoothly incorporated into the gap, andhence, the aforementioned effect can be more remarkably exhibited.

The dipping process may be performed with the pressure within thedipping bath reduced. When the pressure is reduced, bubbles can besuppressed within the melted resin and the melted solder particles canbe more smoothly incorporated into the gap, and therefore, theaforementioned effect can be more remarkably exhibited.

The ratio of the melted solder particles to be included in the meltedresin 14 in this invention, which depends upon the size of the dippingbath 40, is 3 through 6 vol % in the aforementioned exemplified case ofemploying the area array, and can be reduced to approximately ⅕ or lessas compared with the method shown in FIG. 1A.

This is significant for quality control of the dipping bath 40 in thisinvention. Specifically, the melted solder particles dispersed in themelted resin 14 are bonded to one another when they come close to oneanother, but when the bond is repeated, the particles may be grown intoa large solder ball. When the grown solder ball becomes as large as thegap between the semiconductor chip 20 and the circuit board 21, themelted resin 14 cannot be used any more. When the ratio of the meltedsolder particles to be included in the melted resin 14 is set as smallas possible, however, the dipping bath 40 can be kept in a stable statefor a long period of time.

Furthermore, after forming the connectors 22 between the terminals ofthe circuit board 21 and the semiconductor chip 20 in the dipping bath40, the circuit board 21 and the semiconductor chip 20 are taken out ofthe dipping bath 40, and the melted resin 14 having permeated into thegap between the circuit board 21 and the semiconductor chip 20 is cured.Thus, electrical connection between the terminals of the semiconductorchip 20 and the circuit board 21 and the fixation of the semiconductorchip 20 on the circuit board 21 can be continuously performed through aseries of procedures, and hence, it is possible to realize flip-chipmounting with high productivity.

Materials applied in the flip-chip mounting method of this invention arenot particularly specified, and typical examples are as follows:

First, the melted resin 14 is preferably a resin that is in the form ofa liquid or has lower viscosity at the temperature at which the solderparticles are melted. For example, as a thermosetting resin in the formof a liquid at the temperature where the solder particles are melted, anepoxy resin, a polyimide resin, a polyphenylene ether resin, a phenolresin, a fluororesin, an isocyanate resin or the like can be used.Alternatively, as a thermosetting resin having lower viscosity at themelting temperature, all aromatic polyesters, a fluororesin, apolyphenylene oxide resin, a syndiotactic polystyrene resin, a polyimideresin, a polyamide resin, an aramid resin, a polyphenylene sulfide in orthe like can be used.

As the solder particles, a Sn—Ag-based, a Sn—Zn-based or a Sn—Bi-basedsolder can be used. Also, the grain size of the solder particles in anunmelted state is preferably approximately 2 through 30 μm.

Furthermore, the semiconductor chip 20 is not limited to a siliconsemiconductor but may be a silicon-germanium semiconductor or a compoundsemiconductor such as a gallium arsenide semiconductor. In particular,when the method of this invention where small load is applied to thesemiconductor chip is applied to a thin silicon semiconductor, asilicon-germanium semiconductor or a compound semiconductor with smallmechanical strength, a flip-chip mounting body with high reliability canbe realized.

Also, the method of this invention can be applied in the case where asemiconductor chip 20 built on an interposer is flip-chip mounted on acircuit board 21 instead of directly flip-chip mounting thesemiconductor chip 20 on the circuit board 21.

The flip-chip mounting method of this invention is suitable also forbatch processing. For example, as shown in FIG. 3, a plurality ofsemiconductor chips 20 and circuit boards 21 respectively opposing eachother with a given gap provided therebetween are held on a fixing jig31, and under this condition, the plural semiconductor chips 20 andcircuit boards 21 are simultaneously dipped in the dipping bath 40.Thus, the dipping process can be performed as the batch processing.

For the batch processing, it is necessary to prepare a dipping bath 40with a large size to some extent, but on the contrary, the content ofthe melted solder particles in the melted resin 14 can be furtherreduced, and hence, the dipping bath 40 can be more easily controlled.Furthermore, when the batch processing is employed, the throughput isincreased, and the cost may be lowered in mass production process.

Moreover, in order to use the dipping bath 40 more stably, the dippingbath 40 may have a structure as shown in FIG. 4 or 5.

A dipping bath 40 shown in FIG. 4 includes two baths, that is, a firstdipping bath 40 a and a second dipping bath 40 b. The solder particlesincluded in the melted resin 14 contained in the first dipping bath 40 aare controlled to be unmelted, and the solder particles included in themelted resin 14 contained in the second dipping bath 40 b are controlledto be melted. In the case where, for example, Sn—Ag3.0-Cu0.5 (with amelting point of 221° C.) is used as the solder particles, the firstdipping bath 40 a is controlled in a range from room temperature to 200°C. and the second dipping bath 40 b is controlled in a range from 230 to250° C.

In the dipping process, the semiconductor chip 20 and the circuit board21 fixed by the fixing jig are dipped in the first dipping bath 40 afirst, and after a predetermined time, they are taken out of the firstdipping bath 40 a and subsequently dipped in the second dipping bath 40b for a given period of time.

At this point, the dipping process performed in the second dipping bath40 b corresponds to the dipping process shown in FIGS. 2B and 2C, andthe dipping process performed in the first dipping bath 40 a is regardedas preliminary process for it. Specifically, the content of the dippingbath 40 (or 40 b) containing the melted solder particles is preferablynot too large for stabilizing the melted solder particles by preventingtheir aggregation and for reducing the energy consumed in keeping themelted state. On the other hand, when the content of the dipping bath 40is small, the change in proportion of the solder particles in the meltedresin 14 caused through the consumption of the melted solder particlesin the formation of the connectors 22 is so large that it is difficultto keep the dipping bath 40 stable. Therefore, in order to make smallthe proportion change of the solder particles in the melted resin whilepreventing the aggregation of the melted solder particles, thepreliminary dipping process is preferably performed in the dipping bath40 a containing the unmelted solder particles.

Next, a dipping bath 40 shown in FIG. 5A is controlled in such a mannerthat the melted resin 14 contained in the dipping bath 40 has atemperature gradient as shown in FIG. 5B. At this point, the solderparticles included in the melted resin 14 are kept in an unmelted statein a low temperature region and in a melted state in a high temperatureregion. In the case where, for example, Sn—Ag3.0-Cu0.5 (with a meltingpoint of 221° C.) is used as the solder particles, the melted resin 14contained in the dipping bath 40 is controlled to have a temperaturegradient from room temperature to 250° C.

As shown in FIG. 5A, the dipping process is executed by dipping thesemiconductor chip 20 and the circuit board 21 held with the given gapin the low temperature region of the dipping bath 40 for a given periodof time, moving them to the high temperature region and successivelydipping them for a given period of time. The dipping process performedin the low temperature region corresponds to the preliminary processshown in FIG. 4, and the dipping process performed in the hightemperature region corresponds to the dipping process shown in FIGS. 2Band 2C.

Embodiment 2

In the flip-chip mounting method described in Embodiment 1, a circuitboard and a semiconductor chip are dipped in a dipping bath containing amelted resin including melted solder particles for a given period oftime, so as to make the melted solder particles self-assemble betweenterminals of the circuit board and the semiconductor chip for formingconnectors. This technique is also applicable to a bump formationmethod.

FIGS. 6A through 6D are cross-sectional views for showing basicprocedures in a bump formation method according to Embodiment 2 of theinvention. It is noted that detailed description of procedures commonlyperformed in the flip-chip mounting method shown in FIGS. 2A through 2Dis omitted.

First, as shown in FIG. 6A, a substrate 25 having a plurality ofelectrodes 27 is held by a fixing jig 30 so as to oppose a flat plate 26with a given gap (of, for example, 10 through 100 μm) providedtherebetween.

Next, as shown in FIG. 6B, the substrate 25 and the flat plate 26 heldwith the given gap are dipped for a given period of time in a dippingbath 40 containing a melted resin (such as epoxy resin) 14 includingmelted solder particles (of, for example, Sn—Ag-based solder). At thispoint, the melted resin 14 permeates into the gap between the substrate25 and the flat plate 26, and the gap is filled with the melted resin14. In this dipping process, the melted solder particles dispersed inthe melted resin 14 self-assemble on the electrodes 27 with highwettability, so as to form bumps 28 on the electrodes 27 as shown inFIG. 2C. It is noted that the dipping time depends upon the amount ofthe melted solder particles dispersed in the melted resin 14 and istypically preferably 5 through 60 seconds.

At this point, since the melted resin 14 can freely permeate into thegap between the substrate 25 and the flat plate 26 dipped in the dippingbath 40, the melted solder particles dispersed in the melted resin 14are constantly supplied to the gap between the substrate 25 and the flatplate 26, and hence, the bond of the melted solder particles can beuniformly proceeded in the gap.

When the substrate 25 and the flat plate 26 held with the given gap aredipped while being rocked in the dipping bath 40 in a direction shownwith an arrow in FIGS. 6B and 6C, the melted solder particles dispersedin the melted resin 14 can be more forcedly supplied to the gap betweenthe substrate 25 and the flat plate 26, and as a result, the bond of themelted solder particles can be more uniformly proceeded. Alternatively,the same effect can be attained by dipping them while allowing themelted resin to flow in the dipping bath.

Next, after forming the bumps, as shown in FIG. 6D, the substrate 25 andthe flat plate 26 are taken out of the dipping bath 40, and the meltedresin 14 having permeated into the gap between the substrate 25 and theflat plate 26 and the flat plate are removed, and thus, the substrate 25including the bumps formed on the electrodes 27 is completed. It isnoted that the melted resin 14 can be removed with an organic solventsuch as isopropyl alcohol.

At this point, the flat plate 26 may have a plurality of metal patternsin substantially the same shape as the electrodes 27 previously formedin positions opposing the plural electrodes 27 formed on the substrate25. In this case, the procedures shown in FIGS. 6A through 6C aresubstantially the same as the flip-chip mounting procedures shown inFIGS. 2A through 2C. Since the metal patterns have high wettability withthe melted solder particles, the self-assemble of the melted solderparticles on the electrodes 27 can be more uniformly proceeded ascompared with the case where the flat plate 26 has no metal patterns.

The material for the substrate 25 is not particularly specified, but themethod is preferably applied to a circuit board, a semiconductor chip ora semiconductor wafer. In the application to a semiconductor chip, abump-formed semiconductor chip obtained by the bump formation method ofthis invention is used in general flip-chip mounting process to beflip-chip mounted on a circuit board.

Embodiment 3

FIGS. 7 and 8 are diagrams of a mounting apparatus 50 used for executingthe flip-chip mounting method of this invention.

The mounting apparatus 50 shown in FIG. 7 includes a fixing jig 30 forholding a semiconductor chip (not shown) and a circuit board (not shown)to oppose each other with a given gap provided therebetween, a dippingbath 40 containing a melted resin 14 including melted solder particles,and a conveyor 60 for conveying the fixing jig 30 into the dipping bath40, and further includes annealing means 70 if necessary.

In this mounting apparatus 50, the fixing jig 30 holding thesemiconductor chip and the circuit board is dipped in the dipping bath40 by using the conveyor 60, so as to make the melted solder particlescontained in the dipping bath 40 self-assemble between connectionterminals of the circuit board and electrode terminals of thesemiconductor chip, and thus, connectors are formed between theseterminals.

The semiconductor chip and the circuit board on which the connectorshave been formed are taken out of the dipping bath 40 together with thefixing jig 30 by the conveyor 60, and are further transferred to theannealing means 70, in which the melted resin 14 having permeated intothe gap between the semiconductor chip and the circuit board isthermally cured so as to complete a flip-chip mounting body.

The conveyor 60 is provided with a mechanism for rocking the fixing jig30 within the dipping bath 40 while dipping the fixing jig 30 in thedipping bath 40, and the fixing jig 30 holding the semiconductor chipand the circuit board can be rocked within the dipping bath 40 byoperating this mechanism. It is noted that to “rock” includes verticalmovement, horizontal movement and their combination and also includesboth periodic movement and aperiodic movement.

Furthermore, the dipping bath 40 includes a mechanism for allowing themelted resin 14 contained in the dipping bath 40 to flow. The “flow” ofthe melted resin 14 caused by such a mechanism is, for example, wavingmovement and includes both periodic movement and aperiodic movement.

As the annealing means 70, a heating stage (hot plate), a heating box(oven) heated by hot air or infrared, or the like can be used.

When the fixing jig 30 has a mechanism for holding a plurality of pairsof semiconductor chips and circuit boards, the apparatus can cope withthe batch processing.

FIG. 8 shows a mechanism provided for keeping a constant state of themelted resin 14 in the dipping bath 40.

As shown in FIG. 8, a particle counter 80 is provided on a side of thedipping bath 40. The number or grain size of the melted solder particles(not shown) included in the melted resin 14 contained in the dippingbath 40 can be measured by the particle counter 80.

Since the melted solder particles included in the melted resin 14 arebonded to one another with time to grow into larger solder balls, it isa significant control item to monitor the grain size and thedistribution of the melted solder particles contained in the dippingbath 40 for executing the flip-chip mounting of this invention. When thegrain size distribution of the melted solder particles is periodicallymeasured with the particle counter 80, the flip-chip mounting can bestably executed.

Furthermore, the melted solder particles are consumed in forming theconnectors every time the dipping process is performed in the dippingbath 40, and therefore, the amount of the melted solder particlesincluded in the melted resin 14 is gradually reduced. Accordingly, whenthe number of melted solder particles is periodically measured with theparticle counter 80, the flip-chip mounting can be stably executed.

When the grain size and the number of the melted solder particles arefound to exceed a predetermined control criterion through the periodicalmeasurement, it is necessary to perform maintenance for, for example,exchanging the melted resin 14 including the melted solder particlescontained in the dipping bath 40.

The dipping bath 40 may be connected to a circulating apparatus 90 forcirculating the melted resin 14 including the melted solder particles.The circulating apparatus 90 is connected to the dipping bath 40 throughconnecting pips 91 and 92, so that the melted resin 14 including themelted solder particles contained in the dipping bath 40 can flow intothe circulating apparatus 90 through the connecting pipe 91 and returnfrom the circulating apparatus 90 to the dipping bath 40 through theconnecting pipe 92.

Since the circulating apparatus 90 has a larger content than the dippingbath 40, when the state of the melted resin 14 including the meltedsolder particles is kept constant therein, the melted resin 14 containedin the dipping bath 40 can be kept stable.

It is noted that the mounting apparatus 50 shown in FIG. 7 can beapplied as a mounting apparatus for executing the bump formation methodof this invention.

Embodiment 4

As a characteristic of the flip-chip mounting method of this invention,a semiconductor chip and a circuit board held with a given gap providedtherebetween are dipped in a dipping bath containing a melted resinincluding melted solder particles, so as to make the melted solderparticles self-assemble between terminals of the semiconductor chip andthe circuit board for forming connectors. Therefore, the solderparticles included in the melted resin should be in a melted state inthe resin.

However, the solder particles included in the melted resin mutually bondwith time and grow into larger solder balls naturally as describedabove, and therefore, control of the melted resin including the meltedsolder particles is indispensable for keeping the process stable.

The present applicant has proposed the flip-chip mounting method shownin FIGS. 1A through 1C as described above. This flip-chip mountingmethod is characterized by the convection additive 15 further includedin the resin 13 including the solder particles (unmelted), and when theresin 13 is annealed to melt the solder particles, the convectionadditive 15 simultaneously boiled forcedly moves the melted solderparticles, resulting in forming the uniform connectors 22 between theterminals.

In this case, the resin 13 including the unmelted solder particles issupplied onto the circuit board 10 as shown in FIG. 1A by a generalmethod such as the application. Since the amount of the resin 13supplied onto the circuit board 10 is small, however, the amount ofsolder particles included in the resin 13 may be varied. When the amountof solder particles is varied, if the method is applied to the massproduction process, the connectors 22 formed between the terminals arevaried among lots, which may cause quality variation.

In a flip-chip mounting method according to Embodiment 4, the dippingmethod employed in Embodiments 1 through 3 is used as a method forsupplying the resin 13 including the unmelted solder particles onto thecircuit board 10 in the flip-chip mounting method shown in FIGS. 1Athrough 1C.

FIGS. 9A through 9D are cross-sectional views for showing basicprocedures in the flip-chip mounting method according to Embodiment 4 ofthe invention. It is noted that detailed description of procedurescommonly performed in the flip-chip mounting method shown in FIGS. 2Athrough 2D is omitted.

First, as shown in FIG. 9A, a semiconductor chip 20 having a pluralityof electrode terminals 12 is held by a fixing jig 30 so as to oppose acircuit board 21 having a plurality of connection terminals 11 with agiven gap (of, for example, 10 through 100 μm) provided therebetween.

Next, as shown in FIG. 9B, the semiconductor chip 20 and the circuitboard 21 held with the given gap are dipped in a dipping bath 40containing a melted resin (such as epoxy resin) 13 including unmeltedsolder particles (such as Sn—Ag-based solder) and a convection additivefor a given period of time. At this point, the melted resin 13 permeatesinto the gap between the semiconductor chip 20 and the circuit board 21,and the gap is filled with the melted resin 13.

Then, as shown in FIG. 9C, the semiconductor chip 20 and the circuitboard 21 are taken out of the dipping bath 40, and the melted resin 13having permeated into the gap between the semiconductor chip 20 and thecircuit board 21 is annealed. During this annealing, the solderparticles are melted and the convection additive is boiled so as toconvect within the resin 13. Thus, the melted solder particlesself-assemble between the connection terminals 11 of the circuit board21 and the electrode terminals 12 of the semiconductor chip 20, so as toform connectors 22 between the terminals. Thereafter, the resin 13having permeated into the gap between the semiconductor chip 20 and thecircuit board 21 is cured for fixing the semiconductor chip 20 on thecircuit board 21, and thus, a flip-chip mounting body is completed.

In this case, as the convection additive, any additive that is boiledwhen the resin 13 is annealed at a temperature where the solderparticles are melted, such as isopropyl alcohol, butyl acetate, butylCarbitol or ethylene glycol, may be used. Alternatively, an additivethat is decomposed to generate a gas at the annealing temperature forthe resin 13, such as aluminum hydroxide, Dowsonite, ammoniummetaborate, barium metaborate, azodicarbonamide or sodium hydrogencarbonate, may be used.

According to Embodiment 4 of the invention, the melted resin 13contained in the dipping bath 40 is much larger in the amount than theresin 13 supplied onto the circuit board 10 in FIG. 1A, and therefore,the variation in the amount of solder particles included in the resin 13supplied to the gap between the semiconductor chip 20 and the circuitboard 21 can be suppressed by dipping them therein. Accordingly, evenwhen the invention is applied to the mass production process, thevariation in the connectors 22 formed between the terminals can besuppressed, and flip-chip mounting bodies with stable quality can beprovided.

It is noted that the flip-chip mounting method of Embodiment 4 of theinvention can be directly applied to a bump formation method.

FIGS. 10A through 10E are cross-sectional views for showing basicprocedures in a bump formation method according to Embodiment 4 of theinvention. The basic procedures are the same as those in the flip-chipmounting method shown in FIGS. 9A through 9D and hence detaileddescription is omitted.

First, as shown in FIG. 1A, a flat plate 26 is held by a fixing jig 30in a position to oppose a substrate 25 having a plurality of electrodes27 with a given gap provided therebetween.

Next, as shown in FIG. 10B, the substrate 25 and the flat plate 26 heldwith the given gap are dipped in a dipping bath 40 containing a meltedresin 13 including solder particles and a convection additive for agiven period of time. At this point, the melted resin 13 permeates intothe gap between the substrate 25 and the flat plate 26, and the gap isfilled with the melted resin 13.

Then, as shown in FIG. 10C, the substrate 25 and the flat plate 26 aretaken out of the dipping bath 40, and the melted resin 13 havingpermeated into the gap between the substrate 25 and the flat plate 26 isannealed. During this annealing, the solder particles are melted, andthe convection additive is boiled to convect within the melted resin 13,and therefore, the melted solder particles self-assemble on theelectrodes 27 of the substrate 25 so as to form bumps 28 as shown inFIG. 10D.

Thereafter, as shown in FIG. 10E, the melted resin 13 having permeatedinto the gap between the substrate 25 and the flat plate 26 and the flatplate 26 are removed, so as to complete the substrate 25 including thebumps formed on the electrodes 27.

As described so far, according to the flip-chip mounting method and thebump formation method of this invention, a semiconductor chip and acircuit board (a substrate and a flat plate) held with a given gapprovided therebetween are dipped in a dipping bath containing a meltedresin including melted solder particles, so as to constantly supply themelted solder particles dispersed in the melted resin to the gap betweenthe semiconductor chip and the circuit board (between the substrate andthe flat plate), and therefore, bond of the melted solder particles isuniformly proceeded in the gap. As a result, the melted solder particlesuniformly grown self-assemble between connection terminals of thecircuit board and electrode terminals of the semiconductor chip (onelectrodes of the substrate) with high wettability, so as to uniformlyform connectors (bumps provided on the electrodes) for electricallyconnecting the electrode terminals and the connection terminals to eachother.

Furthermore, when the semiconductor chip and the circuit board (thesubstrate and the flat plate) held with the given gap are dipped in thedipping bath while being rocked or dipped in the dipping bath whileallowing the melted resin to flow, the melted solder particles dispersedin the melted resin are more forcedly supplied to the gap between thesemiconductor chip and the circuit board (between the substrate and theflat plate), and hence, the bond of the melted solder particles is moreuniformly proceeded. As a result, the connectors (the bumps) can be moreuniformly formed between the electrode terminals and the connectionterminals (on the electrodes of the substrate). In addition, since themelted solder particles dispersed in the melted resin can be moreefficiently incorporated into the gap, the ratio of the melted solderparticles included in the melted resin can be set to be smaller, andhence, the dipping bath can be more easily controlled.

In conventional mounting of a component such as an IC on a printedboard, a flow solder bath is used. However, merely solder in a meltedstate is contained in the solder bath, which is completely differentfrom the melted resin including the melted solder particles used in thisinvention. Also, the flow solder bath is used for soldering a componentinserted and mounted on a printed board, and the object and thestructure are completely different from those of the flip-chip mountingand the bump formation of this invention.

Although the present invention has been described by way of preferredembodiments, the present invention is not limited to the description butcan be variously modified.

INDUSTRIAL APPLICABILITY

The present invention can provide a flip-chip mounting method and a bumpformation method applicable to flip-chip mounting of a next generationLSI and having high productivity and high reliability.

1. A flip-chip mounting method in which a semiconductor chip having aplurality of electrode terminals is aligned to oppose a circuit boardhaving a plurality of connection terminals for electrically connectingsaid connection terminals of said circuit board and said electrodeterminals of said semiconductor chip to each other, comprising the stepsof: holding said semiconductor chip to oppose said circuit board with agiven gap provided therebetween; dipping said semiconductor chip andsaid circuit board held with the given gap in a dipping bath containinga melted resin including melted solder particles; and after the step ofdipping, taking said conductor chip and said circuit board out of saiddipping bath and curing said melted resin having permeated into the gapbetween said semiconductor chip and said circuit board, wherein in thestep of dipping, said melted solder particles self-assemble between saidconnection terminals of said circuit board and said electrode terminalsof said semiconductor chip, whereby forming connectors between saidterminals, and the step of dipping is performed while rocking saidsemiconductor chip and said circuit board held with the given gap withinsaid dipping bath.
 2. The flip-chip mounting method of claim 1, whereinin the step of holding said semiconductor chip, said semiconductor chipis held to oppose said circuit board with the given gap providedtherebetween by holding said semiconductor chip and said circuit boardwith a fixing jig.
 3. The flip-chip mounting method of claim 2, whereinthe step of holding said semiconductor chip includes a step of holding aplurality of semiconductor chips and a plurality of circuit boards withsaid fixing jig, whereby holding each of said semiconductor chips tooppose each of said circuit boards with a given gap providedtherebetween, and the step of dipping is performed as batch processingfor dipping said plurality of semiconductor chips and said plurality ofcircuit boards simultaneously in said dipping bath.
 4. The flip-chipmounting method of claim 1, wherein the step of dipping is performedwith a pressure in said dipping bath reduced.
 5. The flip-chip mountingmethod of claim 1, wherein the step of dipping is performed in a dippingbath in which said melted resin has a temperature gradient, and saidsolder particles included in said melted resin are kept in an unmeltedstate in a low temperature region and are kept in a melted state in ahigh temperature region, and said semiconductor chip and said circuitboard held with the given gap are dipped in the low temperature regionof said dipping bath for a given period of time before being dipped inthe high temperature region for a given period of time.
 6. A flip-chipmounting method in which a circuit board having a plurality ofconnection terminals is aligned to oppose a semiconductor chip having aplurality of electrode terminals for electrically connecting saidconnection terminals of said circuit board and said electrode terminalsof said semiconductor chip to each other, comprising the steps of:holding said semiconductor chip to oppose said circuit board with agiven gap provided therebetween; dipping said semiconductor chip andsaid circuit board held with the given gap in a dipping bath containinga melted resin including solder particles and a convection additive fora given period of time; and annealing said melted resin having permeatedinto the gap between said semiconductor chip and said circuit boardafter taking said semiconductor chip and said circuit board out of saiddipping bath, wherein in the step of annealing, said solder particlesare melted and said convection additive is boiled to convect within saidmelted resin for making said melted solder particles self-assemblebetween said connection terminals of said circuit board and saidelectrode terminals of said semiconductor chip, whereby formingconnectors between said terminals.
 7. The flip-chip mounting method ofclaim 6, further comprising, after the step of annealing, a step offixing said semiconductor chip on said circuit board by curing saidmelted resin having permeated into the gap between said semiconductorchip and said circuit board.
 8. A flip-chip method in which asemiconductor chip having a plurality of electrode terminals is alignedto oppose a circuit board having a plurality of connection terminals forelectrically connecting said connection terminals of said circuit boardand said electrode terminals of said semiconductor chip to each other,the method comprising steps of: (a) holding said semiconductor chip tooppose said circuit board with a given gap provided therebetween; (b)dipping said semiconductor chip and said circuit board held with thegiven gap in a dipping bath containing a melted resin including meltedsolder particles wherein in the step of dipping, said melted solderparticles self-assemble between said connection terminals of saidcircuit board and said electrode terminals of said semiconductor chip,whereby forming connectors between said terminals, and the step ofdipping is performed in said dipping bath while said melted resin isflowing in said dipping bath; and (c) after the step of dipping, takingsaid semiconductor chip and said circuit board out of said dipping bathand curing said melting resin having permeated into the gap between saidsemiconductor chip and said circuit board.